Means for fumigating with pesticidal compounds



Patented Nov. 22, 1949 MEANS FOR FUMIGATIN G WITH-PESTICIDAL COMPOUNDS Elwyn Jones, Ardrossan, anddohn Stocks. Flanders, West Kilbride, Scotland, assignors to Imperial Chemical Industries Limited, a. corporation of GreatBritain No Drawing. Application March 29, v19116, .Serial No. 658,212. In Great Britain April 9, 1945 12 Claims.

The present invention relates to the art of fumigating with'pesticidal compounds, and more particularly to the provision of simplified or improved means for the thermal production of fumes of pesticidal compounds that are capable of vaporization when suitably heated. The invention is especially valuablefor the purpose of fumigating with combustible pestioidal compounds or pesticidal compounds easily decomposed when overheated. The invention, for instance, facilitates the economical production of a fume comprising an aerosol of the condensed vapor of a pesticidal compound which can deposit on the bounding surfaces of a closed space in which the fume is gener-' ated so as to produce a thin layer of the pesticidal compound that will be active long after the atmosphere is clear of the actual fumes.

One example of a pesticide capable of depositing such a layer when a suitable fumigation method is applied to volatilize it, is the powerful insecticide beta-beta-di-(parachlorophenyl) alphaalpha-alpha-trichloroethane. A further example is the still more powerful insecticide gammabenzene hexachloride which can be applied in the form of a smokeby volatilization from hot plates or by other heatingmethods. In co-pendingapplication 579,683 there is claimed inter alia a method for fumigating an enclosed space to con- .trol pests therein which comprises treating the said space with an aerosol containing a benzene hexachloride.

A combustible candle fumigator, similar to the familiarsulphur candle, would'be a very convenient means for producing the fumes of a vaporizable .pesticidal compound, but in the case of many pesticides it would not be possible tomake up a candle in which a pesticide is drawn into a flame for the purpose of volatilizingit, since the pesticide would therebybe decomposed-or burned with the formation of useless decomposition or combustion products, whereas in the case .of the sulphur candle the active material is the sulphur dioxide produced by the burning of the sulphur.

According to the present invention the means for the thermal production of fumes of the thermally vaporizable pesticidal compound consists of a safety fuse cord wherein one or more of the textile yarn coverings around the powder core is coated or.-impregnated With-the pesticide and the pesticidal compound is preferably protected from direct contact .with the powder core by at least one complete layer of -the textile yarn covering. The pesticidal compound used may be for "instance a solid compound-of organic nature, for-instance a benzene hexachloride or a chlorinated aromatic hydrocarbon derivative. The powder core of the safety fuse cord preferably comprises material yielding gaseous combustion products as it burns, for instance a blackpowder composition, preferably containingno'sulphur.

By the term *powder core we includenot only a core'of black powder or the like somewhat compressed within the textile envelope spun around it; but also a solid non-porous extruded core of plastic material consisting of a mixture of pulverulent oxidizing and reducing agents bound together with a thermoplastic binding agent, for instance a binding agent based on nitrocellulose .and a non-explosive plasticizer, or a polymerized unsaturated resin and a plasticizer, similar to that disclosed in Patent No. 2,363,569, 7

The cord comprising a powder core and a to!!- tile covering, whether or not that in immediate contact with the core, or more than one of the textile coverings, may be coated with a paste comprising the powdered pesticide and an adhesive, or maybe passed through the molten pesticide or a solution of the pesticide, and drawn through a die. While the safety'fuse core is burning, there is a zone creeping along the length of the textile covering somewhat in advance of the actual burning surface of the core thereof, that will be at a temperature'sufiicient to vaporize the pesticide. Thus the conditions are favorable for the vaporization of the pesticide ,intothe atmosphere without actual contact between it and the approaching incandescent burning surface of the powder core. Moreover, the outward expansion of the gaseous combustion products of the powder core and/or the charred textile layer ,in immediate contact with it :causes them to permeate through the pesticide laden textile covering and produce turbulence in the atmosphere immediately around the fuse, thus assistingthe dispersal of the pesticidal vapor. V Y The invention is illustrated in the following examples, in which "the percentages mentioned are by weight:

Example '1 .A .semi-lfuse made .inknown ;manner by spinning a covering of four lea jute and a further covering of 3/12s cotton yarn around a sulphurless gunpowder core was coated with an insecticidal varnish of the following composition.

Per cent China clay 13.7 Beta-beta-di (parachlorophenyl) alpha alpha-alpha-trichloroethane 54.5

Glue 4.5

Water 27.3

After application of this varnish the partly manufactured fuse cord was passed through a die and dried off. A countering with ten 30s/6 cottons was then applied, and then a final coating of a white color varnish of the following composition, the fuse then being passed through a die and dried off:

Per cent China clay 60.6 Glue 12.1 Water 27.3

The weight of the pestioidal compound per foot of the resulting safety fus'e was approximately 0.5 gram. The fuse burns without side-sparking at a rate of about 2 feet per minute and effectively disseminated the insecticidal fume.

Example 2 The procedure was the same as in Example 1', except that in the insecticidal varnish there was employed in place of beta-beta-di-(parachlorophenyl) alpha-alpha-alpha-trichloroethane the same amount of gamma-benzene hexachloride. The resulting safety fuse cord burned in a similar fashion to that prepared according to Example 1, and effectively disseminated the insecticidal fume.

Example 3 A homogeneous composition of 80 parts of pulverulent ingredients consisting of 70 parts red lead, 30 parts potassium nitrate and 20 parts silicon with 20 parts of a thermoplastic binding agent consisting of 50 parts nitrocotton, 18 parts dibutyl phthalate and 2 parts diphenylamine is made up as follows. The silicon is worked into the thermoplastic binding agent contained in a steam jacketed Werner-Pfieiderer mixing machine, at a temperature of about 100 C., until it is well distributed through the plastic. The red lead and potassium nitrate are Worked into the plastic in two stages. The action of the machine is continued until the red lead mixture is well distributed and the mixing has a coherent plastic consistency. The resulting composition is extruded around a copper wire of 36 gauge so that the diameter of the extruded core is 0.048 inch.

The core so extruded is enclosed in a covering of jute yarn followed by a cotton counter.

This semi-fuse is coated with an insecticidal varnish of the following composition:

Per cent China clay 13.7 Beta beta di (parachlorophenyl) alphaalpha alpha trichloroethane 54.5 Glue 4.5 Water 27.3

After the application of this varnish the partly manufactured fuse cord is treated as in Example l.

The resulting safety fuse cord burns in a similar fashion to that prepared according to Example 1, and effectively disseminates the insecticidal compound.

Example 4 The procedure was the same as in Example 1 except that the varnish contained the fungicide pentachlorophenol instead of the insecticide beta-beta di (parachlorophenyll alpha-alphaalpha trichloroethane. The resulting safety fuse cord burned in a similar fashion to that prepared according to Example 1, and effectively disseminated the fungicidal compound.

We claim:

1. A fumigating device which comprises a safety fuse having a combustible core and at least one textile covering surrounding said core, one such covering having a thermally vaporizable pesticidal compound intimately associated therewith, each textile covering being permeable to the gaseous combustion products of said core and said compound being substantially non-volatile at ordinary temperatures.

2. A fumigating device as defined in claim 1 in which said compound is protected from direct contact with said combustible core by at least one complete layer of said textile covering.

3. A fumigating device as defined in claim 1 in which said pesticidal compound is a solid compound of a chlorinated aromatic hydrocarbon derivative.

4. A fumigating device as defined in claim 3 in which said compound is beta-beta di-(parachlorophcnyl) alpha alpha alpha trichloroethane.

5. A. fumigating device as defined in claim 3 in which said compound is gamma-benzenchexachloride.

6. A fumigating device as defined in claim 1 in which said combustible core comprises a black powder composition.

7. A fumigating device as defined in claim 1 in which a uniform coating of a solid pesticidal compound is adhered to at least one of said textile coverings.

8. A fumigating device as defined in claim 1 in which at least one of said coverings has been impregnated with said pesticidal compound.

9. The method of producing a fumigating device which comprises treating a safety fuse, having a combustible core and at least one gas permeable textile covering surrounding said core, with a vaporizable pesticidal compound to intimately associate a quantity of said compound with at least one of said textile coverings, said compound being substantially non-volatile at ordinary temperatures.

10. The method of producing a fumigating device as defined in claim 9 which includes coating said fuse with a composition of said pesticiial compound and an adhesive, and thereafter drawing said fuse through a die to render such coating uniform.

11. The method of producing a fumigating device as defined in claim 9 which includes passing said fuse through a molten bath of said pesticidal compound and thereafter drawing said fuse through a die to render such coating uniform.

12. The method of producing a fumigating device as defined in claim 9 which includes passing said fuse through a solution of said pesticidal compound and thereafter drawing said fuse through a die to render it uniform.

ELWYN JONES. JOHN STOCKS FLANDERS.

(References on following page) REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS- Number FOREIGN PATENTS Number Country Date 4,868 Great Britain of 1902 13,593 Great Britain of 1892 OTHER REFERENCES Slade Chemistry and Industry, October 13, 1945, page 317. (Copy in Library.) 

